Últimos itens adicionados do Acervo: Proceedings Nature

Nature é uma das mais prestigiosas e antigas revistas científicas do mundo: sua primeira edição é de 4 de novembro de 1869. Entre as inúmeras descobertas científicas publicadas na Nature estão a dos raios X, da estrutura em dupla hélice do ADN e o buraco na camada de ozônio.

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‣ Empirical predictions of an intrinsically disordered protein theory approach to glycan/lectin reaction kinetics

Rodrick Wallace
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Manuscript
Português
Newly-developed methods from the theory of intrinsically disordered proteins can be applied to the flexible glycan structures that coat cellular surfaces and provide rich channels for biological information transmission. Extension of a mechanistic 'arm-in-sleeve' model via a nonrigid molecule symmetry analysis leads to expectation of empirical observation of punctuated 'spectral' classifications in glycan/lectin interaction, parameterized by an appropriate index of glycan frond length or other index of topological complexity, possibly requiring groupoid classifications analogous to quasicrystals.

‣ Modeling Compatible Single-Tree Aboveground Biomass Equations of Masson Pine (Pinus massoniana) in South China

Wei Sheng Zeng; Shou Zheng Tang
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Manuscript
Português
In the background of facing up to the global climate change, it is becoming the inevitable demand to add forest biomass estimation to national forest resource monitoring. The biomass equations to be developed for forest biomass estimation should be compatible with volume equations. Based on the tree volume and aboveground biomass data of Masson pine (Pinus Massoniana Lamb.) in south China, the one, two and three-variable aboveground biomass equations and biomass conversion functions compatible with tree volume equations were constructed using the error-in-variable simultaneous equations in this paper. The results showed: (i) the prediction precision of aboveground biomass estimates from one variable equation was more than 95%; (ii) the regressions of aboveground biomass equations improved slightly when tree height and crown width were used together with diameter on breast height, although the contributions to regressions were statistically significant; (iii) for biomass conversion function on one variable, the conversion factor was decreased with growing diameter, but for conversion function on two variables, the factor was increased with growing diameter while decreased with growing tree height.

‣ Unique for human centromeric regions of interphase chromatin homing (CENTRICH) govern dynamic features of chromatin fractal globules

Gennadi Glinsky
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Manuscript
Português
We report the results of the genome-wide alignment of inter- and intra-chromosomal chromatin interactions within the context of interphase chromatin binding to nuclear lamina and nucleolus. For all human chromosomes, a significant correlation exists between binding of chromosomal loci to nuclear lamina and segregation into spatially-defined distinct compartments of genome-wide chromatin interactions identified by Hi-C method. We report identification of near-centromeric intergenic regions on human chromosomes (chr2; chr10; chr17; chr1), which are highly enriched for interphase chromatin homing sites and function as attractors of long-range physical interactions (Centromeric Regions of Interphase Chromatin Homing, CENTRICH). CENTRICH are engaged in 397-1526 pair-wise interactions per 1 Kb distance, which represents 199 - 716-fold enrichment of interphase chromatin homing sites compared to genome-wide average (2-tail Fisher's exact test p values range 2.10E-101 - 1.08E-292). CENTRICH represent unique for human highly homologous DNA sequences of 3.9 - 22.4 Kb in size which are: 1) associated with nucleolus; 2) exhibit remarkably diverse regulatory protein contexts of chromatin state maps; 3) bind multiple intergenic disease-associated genomic loci (IDAGL) with documented long-range enhancer activities and established links to increased risk of developing epithelial malignancies and other common human disorders. For cancer...

‣ Long double stranded RNA is present in scrapie infected cells and tissues

Yervand E. Karapetyan
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Manuscript
Português
The nature of the infectious agent causing scrapie and other Transmissible Spongiform Encephalopathies remains an enigma despite decades of research efforts. The protein-only prion hypothesis posits that abnormal conformer of a host protein is the infectious agent. Virus and virino theories include host-independent nucleic acid as the genome of the infectious agent in addition to protein component (in case of virino a host protein and in case of virus a viral protein). Viral or sub-viral nucleic acids have long been sought in scrapie to explain the existence of multiple agent strains. Many different approaches were undertaken to find such nucleic acid. Despite that no scrapie specific nucleic acid sequences have been found in infected cells or tissues. Most viruses induce synthesis of long double stranded RNA (dsRNA) during their replication in cells. Therefore the presence of long dsRNA would be an indication of viral infection in cells. J2 monoclonal antibody against long dsRNA is a great tool for easy screening of cells and tissues for the presence of suspected unknown viral infection. This antibody has not been used for testing of scrapie infected tissues. Evidence is presented here for long dsRNA in scrapie infected cells and tissues. Such dsRNA is also found in scrapie free tissue culture cells.

‣ Vesicles and lamella: outcome of the changing formation path of a sodium N-lauroylsarcosinate hydrate/1-decanol/water system

Nasima Akter; Faizal Mohamed; Shahidan Radiman; Mohammad I. H. Reza
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Manuscript
Português
Vesicles are closed bilayers that enclose a part of the continuous phase inside the core. In spherical shape, they attain the minimum free energy state. Conversely, lamella with maximum free energy remain in planer bilayer shape in the colloidal dispersion. Even with the same amphiphile concentration the colloidal structures depend on different parameters, many of these already addressed in different reports. However, the effect of mixing procedure as a formation path is unidentified. Here we reported water in 1-decanol and 1-decanol in water; these two different mixing procedures yield vesicles and lamella at the same point of the phase diagram of a sodium N-lauroylsarcosinate hydrate/1-decanol/water system. It was found that the favorable and unfavorable contact of water with the weak tertiary ammonium cation in amino-acid head-group plays the crucial role in this process. Moreover, this weak cationic property of this amphoteric surfactant can be exploited to carry DNA for gene therapy with a nontoxic system instead of cationic.

‣ When Spandrels Become Arches: Neural crosstalk and the evolution of consciousness

Rodrick Wallace
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Manuscript
Português
Once cognition is recognized as having a 'dual' information source, the information theory chain rule implies that isolating coresident information sources from crosstalk requires more metabolic free energy than permitting correlation. This provides conditions for an evolutionary exaptation leading to the rapid, shifting global neural broadcasts of consciousness. The argument is quite analogous to the well-studied exaptation of noise to trigger stochastic resonance amplification in neurons and neuronal subsystems. Astrobiological implications are obvious.

‣ Chromium uptake by Fenugreek

Xanthate D S; Murthy Ch V R; Rajan S C S; Sekhar D M R
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Manuscript
Português
Fenugreek (Trigonella foenum- graecum) is both herb (leaves) and a spice (seed) belonging to the family Fabaceae. Fenugreek leaves and seeds are used in the cuisine of India. Fenugreek also has medicinal value. Fenugreek seeds are known to reduce serum glucose and improve glucose tolerance and hence are prescribed to diabetic patients. In the recent past supplemental Chromium is being prescribed to diabetic patients to activate (increased- insulin binding, insulin receptor number, insulin receptor phosphorylation) insulin. Plants can uptake substantial quantities of toxic metals from contaminated soils if these soils are well ameliorated. It is then probable that the medicinal efficacy of Fenugreek in the case of diabetes could be enhanced if it takes up chromium from the soil. Preliminary studies are being conducted to note the chromium uptake by Fenugreek from soils which are applied with potassium dichromate.

‣ Integrative concept of homeostasis: translating physiology into medicine

Ivan Spasojevic
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Manuscript
Português
To truly understand living systems they must be viewed as a whole. In order to achieve this and to come to some law to which living systems obey, data obtained on cells, tissues and organs should be integrated. Because there are no such laws yet, there is usually a long path for physiological findings obtained by reductionist approaches to be translated into medical practice. The concept and accompanying equations of homeostasis presented here are aimed to develop biological laws and to bridge this gap between physiology and medicine. The concept of homeostasis takes into account energy input and output, enlisting all relevant contributors. In homeostasis, changes in the input should equal changes in the output within any specific period of time. What I suggest here is that if the system is out of homeostasis, the homeostasis may be regained by changing any of the input or output components in a proper manner, not only the one that has been changed first. It is important to note that the concept is primary addressing adult human physiology. Proposed equation should enable for the new lab findings regarding any pathophysiological conditions to find a more direct use in medicine. It should also ease ‘decision making’ in medicine and make therapy development and treatment outcome more straightforward and predictable. Finally...

‣ Studies on the Accumulation of Chromium in Fenugreek

Xanthate D S; Murthy Ch V R; Rajan S C S; Sekhar D M R
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Manuscript
Português
Studying Cr uptake by Fenugreek, we note that the maximum concentration of Cr takes place in the shells of the pods followed by leaves, stems and seeds in that order. Interestingly, applied higher doses of Cr does not increase accumulation of Cr in the stems, rather Cr content in the stems levels off. However, the maximum dispersal/distribution of Cr taken up is in the leaves.

‣ Isoglitter

Michael J. Bucknum; Eduardo A. Castro; Bin Wen
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Manuscript
Português
Described herein is a novel crystalline pattern in space group Ammm, that is a model of a C allotrope. This so-called isoglitter structure-type is an analogue to the graphite-diamond hybrids. A DFT geometry optimization and band structure calculation indicates that the lattice is metallic in a C realization.

‣ An integrated solution for rapid biosensing combining linker free binding, freeze drying and high sensitivity ellipsometric detection

Yongbai Yin; David R. McKenzie; Keith Fisher; Chuan Guo; Neil Nosworthy; Marcela M. Bilek
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Manuscript
Português
A novel integrated biosensor methodology is proposed and demonstrated. The methodology utilizes a nitrogen-containing plasma polymer to achieve linker-free binding of biorecognition molecules that allows the sensor surface to be freeze dried for long shelf life under ambient conditions. The sensor is configured for single wavelength ellipsometric detection providing a low cost, versatile, and rapid sensing and diagnosis platform suitable for a wide range of applications and end-users. The merits of the methodology were demonstrated using three antigen-antibody pairs.

‣ Screening of actinobacteria for antimicrobial activities by a modified "Cross-Streak" method

Nandkumar Kamat; Sonashia Velho-Pereira
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Manuscript
Português
New molecule discovery from natural sources, such as that of actinobacteria, has proved to be an interesting area in antibiotic research, as most of these antibiotics are difficult to synthesize. Out of 30 actinobacterial cultures screened for antimicrobial activity, 28 cultures were found to produce active products against various pathogenic microorganisms such as Gram-negative, Gram-positive bacteria and yeast, using a ‘modified cross streak method.' The modified method helped in easy quantification of results and also in ruling out probable mutual antibiosis. 53%, 13% and 10% of tested actinobacterial strains belonging to Streptomyces, Micromonospora and Actinomadura genera, respectively, showed the ability of producing antimicrobial compounds. Streptomyces sp. strain MMA-5 showed the highest percentage multispecific antibiosis efficiency score value. Broad antibiotic spectrum activity was exhibited by Streptomyces sp. strain MMA-2 and Micromonospora sp. strain MMA-8. The multidrug resistant human pathogenic yeast strain Candida albicans was inhibited by 18 actinobacterial strains.

‣ "Dark Mediators" of Proteins as Revealed by NMR in Water: Residue-selective Anion Bindings that are Masked by Pre-existing Buffer

Jianxing Song; Linlin Miao; Haina Qin
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Manuscript
Português
Ions are commonly believed to impose their effects on proteins by unspecific electrostatic screening. Here, by NMR we reveal that in water sulfate, chloride and thiocyanate are able to bind a well-folded WW domain at distinctive residues and affinities, which is surprisingly masked by the pre-existing buffer. Our study reveals that the specific anion binding is so ubiquitous and consequently no longer negligible in establishing "postreductionist framework" for protein biochemistry.

‣ Bacteriophages as a model for studying carbon regulation in aquatic system

Swapnil G. Sanmukh; Waman N. Paunikar; Sandhya Swaminathan; Satish K. Lokhande
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Manuscript
Português
The interconversion of carbon in organic, inorganic and refractory carbon is still beyond the grasp of present environmentalists. The bacteria and their phages, being the most abundant constituents of the aquatic environment, represent an ideal model for studing carbon regulation in the aquatic system. The refractory dissolved organic carbon (DOC), a recently coined terminology from the microbe-driven conversion of bioavailable organic carbon into difficult-to-digest refractory DOC by microbial carbon pump (MCP), is suggested to have the potential to revolutionize our view of carbon sequestration. It is estimated that about 95% of organic carbon is in the form of refractory DOC, which is the largest pool of organic matter in the ocean. The refractory DOC is supposed to be the major factor in the global carbon cycle whose source is not yet well understood. A key element of the carbon cycle is the microbial conversion of dissolved organic carbon into inedible forms. The time studies of phage-host interaction under control conditions reveal their impact on the total carbon content of the source and their interconversion among organic, inorganic and other forms of carbon with respect to control source. The TOC- analysis statistics stipulate an increase in inorganic carbon content by 15-25 percent in the sample with phage as compared to the sample without phage. The results signify a 60-70 fold increase in inorganic carbon content in sample with phage...

‣ Reduced GABA-B/GIRK-mediated regulation of the VTA following a single exposure to cocaine

Brian Cadle; Andrew Varnell; Donald C. Cooper
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Manuscript
Português
In this paper, Arora and colleagues expand on their previous work on GIRK channels in the ventral tegmental area (VTA) presenting evidence that a single exposure to cocaine reduces inhibitory GABAergic transmission to dopamine (DA) neurons in the ventral tegmental area. Mice receiving i.p. injections of cocaine saw a short lived (1-5 days) decrease in GABAb mediated G-protein coupled inwardly-rectifying potassium (GIRK) currents in DA neurons in the VTA. This decrease parallels an NMDA-mediated increase in the frequency of glutamatergic neurotransmission. Chronic cocaine injections had no additional effects beyond those seen with single injections. Though they found no change in mRNA levels for GABAb receptors, GIRK channels, or RGS-2 (a G-protein regulator), immunoelectron microscopy indicated a decrease in levels of GIRK channels in the plasma membrane of the dendrites of VTA DA neurons. The cocaine-mediated decrease in GIRK currents was abolished in the presence of D2/3R antagonist sulpiride, but not in the presence of D1/5 antagonist SCH23390, indicating a link between D2/3 receptor activation and GIRK activity. Interestingly, the addition of quinpirole, a D2/3 agonist, elicited similar GIRK currents, though they were smaller than those mediated by GABAb receptors. Similarly...

‣ Solubilization of M2 Transmembrane Peptide of Influenza A in Pure Water: Implications for Emergence of Proteins and Protein-embedded Primeval Membranes in Unsalted Oceans

Jianxing Song; Linlin Miao
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Manuscript
Português
We demonstrated that M2 transmembrane peptide, one of the most hydrophobic sequences in nature, can be solublized to at least ~100 µM in unsalted water without any lipid molecules. Strikingly, the M2 peptide also forms a highly-helical conformation in water which remains almost unchanged even at 95 ºC, as characterized by CD spectroscopy. Our result has critical implications in understanding emergence of proteins and protein-embedded primeval membranes in unsalted oceans.

‣ The legacy of bio-molecules as a bio-fertilizer: Context of single cell fertilizer Isolation and partial characterization of an amylolytic bacterium

Sribir Sen; Anwesha Banerjee; Sanghamitra Sanyal
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Manuscript
Português
Repeated cultivation of crop plants is the reason for the depletion of nutrients in an agricultural land. Therefore, modern procedures of agriculture cascaded with the addition of organic and inorganic fertilizers, the use of insecticides and pesticides, the addition of proper water, etc. Various inorganic molecules are used as fertilizers. However, the use of organic manures is also in practice. They have many roles such as improving soil porosity, air holding capacity, water holding capacity, structure, texture, etc. Agricultural scientists suggest using organic molecules for many reasons. Bio-fertilizers of many kinds are used by farmers of all nations. However, these fertilizers are unable to cause tremendous effects on the growth and development of crop plants, even though these fertilizers have cumulative effects. The present work focuses on the use of bio-molecules as bio-fertilizer. To make these molecules, an amylolytic bacterium was isolated and partially identified based on microscopic observations and biochemical tests. The optimum pH, temperature, substrate concentration, etc. were studied. The optimum pH and temperature for the growth of the isolate were pH 7.0 and 37.0°C, respectively. However, the organism grows even in 60.0°C. The organism uses four commonly available natural substrates as carbon source. Among these...

‣ Synaptic state matching: a dynamical architecture for predictive internal representation and feature perception

Saeed Tavazoie
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Manuscript
Português
Here we consider the possibility that a fundamental function of sensory cortex is the generation of an internal simulation of sensory environment in real-time. A logical elaboration of this idea leads to a dynamical neural architecture that oscillates between two fundamental network states, one driven by external input, and the other by recurrent synaptic drive in the absence of sensory input. Synaptic strength is modified by a proposed synaptic state matching (SSM) process that ensures equivalence of spike statistics between the two network states. Remarkably, SSM, operating locally at individual synapses, generates accurate and stable network-level predictive internal representations, enabling pattern completion and unsupervised feature detection from noisy sensory input. SSM is a biologically plausible substrate for learning and memory because it brings together sequence learning, feature detection, synaptic homeostasis, and network oscillations under a single parsimonious computational framework.

‣ The biological cost of consciousness

Bernard J. Baars
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Manuscript
Português
Some philosophers maintain that consciousness as subjective experience has no biological function. However, conscious brain events seem very different from unconscious ones. The cortex and thalamus support the reportable qualitative contents of consciousness. Subcortical structures like the cerebellum do not. Likewise, attended sensory stimuli are typically reportable as conscious, while memories of those stimuli are not so reportable until they are specifically recalled. Reports of conscious experiences in normal humans always involve subjectivity and an implicit observing ego. Unconscious brain events are not reportable, even under optimal conditions of report. While there are claimed exceptions to these points, they are rare or poorly validated. Normal consciousness also implies high availability (rapid conscious access) of the questions routinely asked of neurological patients in the Mental Status Examination, such as common sense features of personal identity, time, place, and social context. Along with “current concerns,” recent conscious contents, and the like, these contents correspond to high frequency items in working memory. While working memory contents are not immediately conscious...

‣ Ligand induced cleavage and nuclear localization of the rice XA21 immune receptor

Chang-Jin Park; Pamela C. Ronald
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Manuscript
Português
The rice XA21 receptor confers immunity to the Gram-negative bacterial pathogen, _Xanthomonas oryzae_ pv. _oryzae_ (_Xoo_) upon recognition of the conserved microbial signature AxY^S^22. Here, we demonstrate that the intracellular kinase domain of XA21 translocates to the nucleus upon AxY^S^22-mediated perception and that this translocation event is required for XA21-mediated immunity.